Telescopic boom for a vehicle crane

ABSTRACT

The invention relates to a telescopic boom for a vehicle crane, comprising a base housing ( 1 ), which may be mounted to an upper construction on the vehicle crane in a horizontal joint ( 2 ), at the lower end thereof and has further horizontal joint ( 3 ), to which a tipping cylinder, for inclination of the telescopic boom, which may be connected to the upper construction, may be connected and several telescopic stages ( 4 - 11 ), running either in each other or in the base housing ( 1 ), all of which may be telescoped by means of a telescoping device ( 12 ) directly connected thereto and which may be locked relative to each other in the telescoped position. One of the telescoping stages ( 4 - 11 ) is embodied from two part pieces ( 4   a, b ) may be locked together by stage ( 4 ), and both part pieces ( 4   a, b ) are pivoted together by means of a hinge. The part pieces ( 4   a, b ) may be locked together by means of a locking device in respect of their longitudinal axis in a coaxial orientation and in at least one position, bent relative to each other. According to the invention, the hinge and locking device on the bending telescopic stage ( 4 ) lie within the internal contour of the next largest telescopic stage ( 5 ).

DESCRIPTION

[0001] The invention relates to a telescopic boom for a vehicle crane having the features of the preamble of patent claim 1.

[0002] A vehicle crane with a generic telescopic boom is disclosed by EP 0 970 914 A2. The vehicle crane disclosed there has a lower carriage provided with a road chassis and an upper carriage arranged thereon such that it can rotate about a vertical axis. The upper carriage is provided with a telescopic boom which has a base housing which, at its lower end, has a horizontal rotary joint to be fixed to the upper carriage. A further rotary joint is arranged approximately in the central region of the base housing, on its underside. This rotary joint is used to attach a hydraulic tilting cylinder which, in turn, is rotatably mounted on the upper carriage and is used to the erect the telescopic boom and to hold the inclination respectively desired during working use. Arranged in the base housing are a large number of telescopic stages which are guided in one another and in the base housing (outermost telescopic stage). All the telescopic stages can be moved out from their retracted position into a telescoped position by means of a telecopier which can be coupled directly in each case to the telescopic stage to be moved and which is preferably constructed as a hydraulic cylinder-piston system. The telescopic stages can be locked mechanically with respect to one another in the telescoped position in order that they cannot slide back under the action of the load to be lifted or the inherent weight when inclined. One of the telescopic stages of this telescopic boom comprises two portions in its axial length which can be pivoted in relation to each other by means of a hinge, so that the result is angling within this telescopic stage. By means of a locking device, the two portions can be locked to each other with regard to their longitudinal axes in a coaxial alignment and in at least one position angled in relation to each other. This locking device is constructed as a hydraulic cylinder-piston unit and is arranged on the outside of the telescopic stage that can be angled, in such a way that the cylinder is pivotably mounted in a bearing block connected on the outside to a portion of the telescopic stage that can be angled, while the piston rod of the cylinder-piston unit is attached by means of a rotary joint to a holding arm which is firmly connected on the outside to the other portion of the telescopic stage that can be angled. On the under side of the telescopic stage that can be angled, the two portions are connected to each other by a hinge likewise located on the outside. The angled point of the telescopic stage that can be angled is arranged approximately in the upper fifth of this telescopic stage. Because of the arrangement of the hinge and the locking device, the telescopic stage that can be angled can be retracted into the next largest telescopic stage only as far as the angled point. Since the permissible transport length of the boom in the telescoped-in state is limited, the telescopic stages surrounding the telescopic stage that can be angled, and the base housing, are designed to be shorter than in the case of a comparable vehicle crane without a telescopic stage that can be angled. The maximum extendable length of the telescopic boom is thus reduced.

[0003] It is an object of the present invention to improve a telescopic boom of the generic type to the effect that, without the necessity to use an additional boom, the telescopable length of the boom is increased considerably.

[0004] This object is achieved by the features specified in the characterizing part of patent claim 1. Advantageous developments of the invention emerge from the dependent claims.

[0005] The present invention avoids the disadvantage of shortening the rear telescopic stages with respect to the telescopic stage that can be unwound and of the base housing in such a way that the hinge and the locking device of the telescopic stage that can be angled are arranged in such a way that they lie within the inner contour of the next largest telescopic stage. This makes it possible to retract the telescopic stage that can be angled completely into the next largest telescopic stage by means of the telescoping device. The next largest and all the further larger telescopic stages can thus maintain the full length as in the case of a conventional telescopic boom. The hinge and the locking device are expediently arranged in such a way that they do not project beyond the outer contour predefined by the respective hollow profile of the telescopic stages, that is to say they are arranged in the interior of the hollow profile.

[0006] The innermost telescopic stage is preferably configured as a telescopic stage that can be angled. However, in principle it is also possible to configure a telescopic stage lying further out to be angled, that is to say for example the second last or third last telescopic stage. In any case, it is preferable for the telescopic stage that can be angled to be arranged in the upper third of the fully extended length of the telescopic boom.

[0007] Although the hinge may project slightly beyond the outer contour of the hollow profile of the telescopic stage that can be angled, since there is regularly a certain minimum distance between two telescopic stages which are guided into each other, it is recommended to arrange the hinge to be located completely on the inside on the underside of the telescopic stage that can be angled. Expediently, it has least one, in particular a pair, of joint pins which in each case interact with a joint lug and a joint fork, the joint lug being connected to one portion and the joint fork to the other portion of the jointed stage that can be angled.

[0008] In a corresponding way, the locking device is likewise expediently arranged to be located completely on the inside on the upper side of the telescopic stage that can be angled, so that the outer contour of the hollow profile of the telescopic stage that can be angled projects only a little, if possible not at all.

[0009] The locking device of the telescopic boom according to the invention can be formed by one or else a plurality of hydraulic cylinder-piston systems or else, for example, by one or more threaded spindle drives, which are each case arranged on the inner side of the two portions of the telescopic stage that can be angled. In this way, stepless adjustment of the angle between the two portions may be made possible. As a rule, however this is not even required. For this reason, within the context of the present invention, preference is given to a solution in which the locking device is formed as a pin locking system, which is constituted by a simple and therefore particularly cost-effective solution which is less susceptible to faults.

[0010] For this purpose, at least one locking pin, in particular a pair of locking pins, is provided in the locking device, which pins, given a coaxial alignment of the longitudinal axes of the portions of the telescopic stage that can be angled, being capable in each case of being inserted into mutually coaxial drilled holes in a locking fork which is connected to one portion, and a locking lug which is connected to the other portion, in order to achieve a locking of this coaxial alignment, and capable of being withdrawn from the drilled holes, canceling the locking. In this case, the diameter of the coaxial drilled holes corresponds to the diameter of the locking pins. In this way, absolutely secure normal operation of the telescopic stage that can be angled can be ensured, in which the two portions are therefore not angled with respect to each other. In order to fix an angled position of the two portions, the locking device preferably has a retaining lug which, by means of retaining pins, is in each case connected to a retaining fork, the retaining forks in turn in each case being firmly connected on the inside to one of the two portions of the telescopic stage that can be angled. The retaining lug is expediently provided with a slot along its longitudinal axis, the diameter (width) of which hole corresponds to the diameter of the retaining pins, so that the latter can slide relatively through the slot. The axial length of this slot is designed such that the two retaining pins bear on the respective semi-cylindrical inner surfaces in the two end regions of the slot in the angled position of the two portions, so that a stop position is provided. When the two portions are extended from the angled position into the non-angled coaxial position, the two retaining pins can slide unimpeded within the slot, so that the extension is possible without removal of the retaining pins. Of course, in this case it is not possible to fix intermediate positions of the angling. If this should be required, however, for example retaining lugs with a different length of the slot can be used. In principle, it would also be possible to provide a plurality of drilled holes spaced apart from one another in the axial direction in the retaining lugs, into which holes the retaining pins are inserted in each case at an appropriate angular position. However, this would require undesired mounting effort. Of course, it is also possible to use more than one combination of retaining lug, retaining fork and retaining pins.

[0011] The use of a single combination of this type is completely adequate, however.

[0012] In a preferred embodiment, the invention provides for the locking pins in each case to be fixed to a pin carrier, which can be moved parallel to the axes of the drilled holes in the locking fork and the locking lug. The pin carriers can preferably be moved by means of a threaded spindle drive. The drive for the movement of the pin carriers can be of a hydraulic, pneumatic, electric-motor or else electromagnetic type. However, because of the design, which is particularly simple, little susceptible to faults and less complicated, both with regard to the outlay on construction and to the operation, a drive of a threaded spindle drive for the pin carriers by means of a hand crank is preferred. In order to require as little overall space as possible with regard to not exceeding the outer contour of the hollow profile of the telescopic stage that can be angled, such a hand crank can be configured to be removable. However, the hand crank preferably has a drive shaft which can be displaced axially in a corresponding hollow shaft belonging to the threaded spindle drive and is firmly guided in the latter so as to rotate with it. As a result, for the purpose of operation, this hand crank can be pulled out of the interior of the hollow profile of the telescopic stage through an appropriate opening in the side wall of the latter and brought into the working position. Furthermore, it is particularly worth recommending that this hand crank be equipped with a handle that can be folded in.

[0013] In the following text, the invention will be explained in more detail using an exemplary embodiment illustrated in the figures, in which:

[0014]FIG. 1 shows a telescopic boom according to the invention in a completely telescoped-in position and in a position with the innermost telescopic stage, which can be angled, telescoped out,

[0015]FIG. 2 shows a bending point in a coaxial alignment of the portions of the telescopic stage that can be angled,

[0016]FIG. 3 shows a plan view of the bending point,

[0017]FIG. 4 shows the bending point with the portions of the telescopic stage angled,

[0018]FIG. 5 shows an axial cross-section according to the line A-A in FIG. 2,

[0019]FIG. 6 shows an axial cross-section according to the line C-C in FIG. 4, and

[0020]FIG. 7 shows a section according to the line B-B in FIG. 5.

[0021]FIG. 1 shows a telescopic boom according to the invention in axial longitudinal section in two positions. In the upper illustration, all the telescopic stages 4-10 which can be telescoped out of a base housing 1 of the telescopic boom are completely retracted into the base housing 1. This position corresponds to the transport position of the telescopic boom. In the lower illustration of FIG. 1, only the innermost telescopic stage 4 has been moved out of the base housing 1 and out of the next largest telescopic stage 5 by means of the hydraulic telescoping device 12, so that the bending point 32 between the two portions 4 a, 4 b of the telescopic stage 4 that can be angled is exposed, that is to say is no longer enclosed by the telescopic stage 5. The constructional configuration of the bending point 32 will be discussed in more detail further below. At its lower (right-hand) end, the base housing is provided with a rotary joint 2, with which the telescopic boom according to the invention can be fixed to the upper construction of a vehicle crane such that it can be pivoted about a horizontal axis of rotation. On the longitudinal side of the base housing 1, which is to be viewed as the underside in the working position, there is arranged a further rotary joint 2, which likewise has a horizontal axis of rotation and is used to connect a hydraulic tipping cylinder, with which the telescopic boom reaches the inclination required for the task respectively to be dealt with and maintains it under load.

[0022] The further FIGS. 2 to 7 reveal in detail the construction and functioning of the bending point 32 of the telescopic boom according to the invention. In FIG. 2, the bending point is illustrated as a side view in a telescopable position, in which the two portions 4 a, 4 b of the telescopic stage 4 that can be angled are aligned in a coaxial position in relation to each other and are fixed with respect to each other in this position. For this purpose, on the inner side of the hollow profile of the two portions 4 a, 4 b there is arranged a hinge which, as revealed in particular by FIG. 5, has two joint pins 13 a, 13 b and two joint lugs 14 a, 14 b and two joint forks 15 a, 15 b. The joint lugs 14 a, 14 b are in each case inserted into the interspace formed by the mutually parallel sheet metal parts of the joint forks 15 a, 15 b and in each case the two are provided with coaxial drilled holes whose diameter corresponds to the diameter of the respective joint pin 13 a, 13 b. The joint pins are inserted into these drilled holes and fixed axially, so that a rotary joint is produced as a hinge which is always present. In order to be able to fix the two portions 4 a, 4 b in their coaxial alignment in relation to each other, constructional precautions are taken as a locking device on the inner side of the hollow profile, in the upper part of the latter, which correspond to the hinge on the lower side. These in each case comprise a locking fork 18 a, 18 b, a locking lug 17 a, 17 b inserted into these locking forks 18 a, 18 b, the locking forks 18 a, 18 b and the locking lugs 17 a, 17 b being provided with coaxial drilled holes, and in each case a locking pin 16 a, 16 b which can be inserted into these drilled holes and whose outer diameter corresponds to the hole diameter. In FIG. 3 and in FIG. 5, the locking pins 16 a, 16 b are shown in the locking position. Under these conditions, the innermost telescopic stage 4 behaves like a conventional single-part telescopic stage, that is to say can be telescoped in and out. The locking pins 16 a, 16 b are in each case fixed by means of a screw connection to the front of the upper end of a pin carrier 23 a, 23 b which, at its lower end, has a threaded hole running parallel with the longitudinal axis of the locking pin 16 a, 16 b (FIG. 5). The two pin carriers 23 a, 23 b are arranged in parallel with each other in such a way that the two threaded holes are aligned coaxially. An adjusting shaft 24 which has two threaded sections 25 a, 25 b, corresponding to the threaded holes is guided through the threaded holes. The two threaded sections 25 a, 25 b, and also the two threaded holes, have pitches opposed to each other. When the adjusting shaft 24 is rotated, therefore, the two pin carriers 23 a, 23 b are moved either toward each other or away from each other, depending on the direction of rotation. In this way, the locking pins 16 a, 16 b can be moved out of the drilled holes in the locking lugs 17 a, 17 b and locking forks 18 a, 18 b or moved into said drilled holes as required. In order that the pin carriers 23 a, 23 b cannot corotate with the adjusting shaft 24, they are guided in slots 27 a, 27 b (FIG. 5 and FIG. 7) such that they are fixed against rotation but are longitudinally displaceable. The adjusting shaft 24 is mounted within the portion 4 a of the telescopic stage 4 such that it can rotate but is axially undisplaceable. At its left-hand end, the adjusting shaft 24 is configured as a hollow shaft and provided with a slot 30, which extends parallel to the longitudinal axis of the adjusting shaft 24. The drive shaft 28 of the hand crank 26 can be inserted into the hollow shaft part of the adjusting shaft 24. At its right-hand end, the drive shaft 28 has a driver pin 29 which protrudes radially and projects through the slot 30. In this way, the driver pin 29 forms a stop for the withdrawal of the drive shaft 28 out of the hollow shaft part of the adjusting shaft 24. At the same time, this driver pin 30 effects a rotationally fixed connection between the drive shaft 28 and the adjusting shaft 24. In the left-hand side wall of the hollow profile of the portion 4 a, FIG. 5 reveals a wall opening which correspond the extent of the hand crank 26. Since the hollow shaft part 24 has a length corresponding to the axial length of the drive shaft 28, in this way the hand crank 26 can be pushed completely into the hollow profile, as emerges from FIG. 6. The handle of the hand crank 26 can advantageously be folded in, so that, when it is folded, no disruptive parts project beyond the outer contour of the hollow profile.

[0023] In order to be able to bend the two portions 4 a, 4 b with respect to each other at the bending point 30, the locking by the locking pins 16 a, 16 b must be canceled by means of appropriate actuation of the adjusting shaft 24, that is to say the locking pins 16 a, 16 b must be moved out of the associated drilled holes in the locking forks 18 a, 18 b and the locking lug 17 a, 17 b. Of course, it is possible that the locking pins 16 a, 16 b in each case still project into the drilled hole in the respective inner part of the locking cables 18 a, 18 b, as emerges from FIG. 6, which, like FIG. 4, shows the unlocked position. The locking lug 17 a, 17 b is in each case pivoted out of the associated locking fork 18 a, 18 b in the angled position of the two portions 4 a, 4 b. In order to fix the two portions 4 a, 4 b in relation to each other in the respectively desired angled position with the effect of a stop, an appropriate retaining device is provided in the upper part of the hollow profile of the telescopic stage 4 and prevents the angle between the two portions 4 a, 4 b being able to change beyond a predefined value under the action of the load to be lifted or the inherent weight of the angled portion 4 a. This retaining device is arranged in the center between the two locking forks 18 a, 18 b and has two retaining forks 21 a, 21 b, which in each case are fixed to one of the two portions 4 a, 4 b. Positioned between the retaining forks 21 a, 21 b is a retaining lug 20, which is provided with a slot 22 which extends in the direction of the longitudinal axis of the retaining lug 20. The two retaining forks 21 a, 21 b are in each case provided with through holes into which in each case a retaining pin 19 a, 19 b is inserted such that it is axially undisplaceable. The diameter and the width of the slot 22 correspond to the diameter of the retaining pins 19 a, 19 b, so that the retaining lug 20, whose slot 22 has a length which is substantially greater than the axial spacing of the two retaining pins 19 a, 19 b (FIG. 3), is held by the retaining pins 19 a, 19 b such that it can slide. Therefore, as illustrated in FIG. 4, the two portions 4 a, 4 b can be pivoted towards each other about the common axis of the joint pins 13 a, 13 b and are only bounded in this pivoting movement when reaching the end stop position of the two retaining pins 19 a, 19 b in the slot 22. FIGS. 2 and 3 further reveal the arrangement of a sensor 31, with which it is possible to monitor whether the hand crank 26 has been pushed in properly and does not impede the action of telescoping in the telescopic stage 4.

[0024] The configuration according to the invention provides a telescopic boom all telescopic stages of which can be extended by means of a common telescoping device and whose length, including the length of the base housing, does not have to accept any type of shortening as compared with a conventional telescopic boom, since the bending point of the telescopable telescopic stage can be retracted completely into the telescopic stage in each case surrounding the telescopic stage that can be bent. The constructional precautions required for this purpose can be of a purely mechanical type and are therefore comparatively cost-effective and in any case extremely secure in operation. Since, in order to actuate the unlocking of the bending point, only very little effort is required and bending is only comparatively infrequently necessary, this actuation can readily be carried out by hand. In order to bring the bent telescopic stage into a coaxial alignment of its two portions again, the tip of the boom merely needs to be placed on a substrate (for example the ground) and lowered further until the drilled holes in the locking lugs and locking forks are aligned with one another and the locking pins can be inserted. After that, the last piece of the telescopic boom can also be telescoped in completely.

[0025] List of designations:

[0026]1 Base housing

[0027]2 Rotaryjoint

[0028]3 Rotary joint

[0029]4 Innermost telescopic stage

[0030]4 a, b Portions of the innermost telescopic stage

[0031]5-11 Telescopic stages

[0032]12 Telescoping device

[0033]13 a, b Joint pin

[0034]14 a, b Joint lug

[0035]15 a, b Joint fork

[0036]16 a, b Locking pin

[0037]17 a, b Locking lug

[0038]18 a, b Locking fork

[0039]19 a, b Retaining pin

[0040]20 Retaining lug

[0041]21 a, b Retaining fork

[0042]22 Slot

[0043]23 a, b Pin carrier

[0044]24 Adjusting shaft

[0045]25 a, b Threaded section

[0046]26 Hand crank

[0047]27 a, b Slot

[0048]28 Drive shaft

[0049]29 Driver pin

[0050]30 Slot

[0051]31 Sensor

[0052]32 Bending point 

1. A telescopic boom for a vehicle crane, comprising a base housing (1) which, at its lower end, can be mounted in a horizontal rotary joint (2) on an upper construction of the vehicle crane and has a further horizontal rotary joint (3), to which a tipping cylinder that can be connected to the upper construction can be attached in order to incline the telescopic boom, and comprising a plurality of telescopic stages (4-11) which are in each case guided in one another or in the base housing (1), which can all be telescoped by means of a telescoping device (12) that can be coupled directly to the respective telescopic stage, and can be locked with respect to one another in the telescoped position, one of the telescopable telescopic stages (4-11) being assembled as a telescopic stage that can be angled in its axial length from two portions (4 a, b) and the two portions (4 a, b) being capable of being pivoted in relation to each other by means of a hinge, and the portions (4 a, b) being capable of being locked to each other by means of a locking device with regard to their longitudinal axes in a coaxial alignment and in at least one position angled in relation to each other, characterized in that the hinge on the locking device of the telescopic stage (4) that can be angled lies within the inner contour of the next largest telescopic stage (5).
 2. The telescopic boom as claimed in claim 1, characterized in that the telescopic stage (4) that can be angled is the innermost of the telescopic stages (4-11).
 3. The telescopic boom as claimed in one of claims 1-2, characterized in that the hinge is arranged on the inside on the underside of the telescopic stage (4) that can be angled.
 4. The telescopic boom as claimed in one of claims 1-3, characterized in that the hinge has at least one, in particular a pair of, joint pins (13 a, b), which each interact with a joint lug (14 a, b) which is connected to one portion (4 a), and a joint fork (15 a, b) which is connected to the other portion (4 b).
 5. The telescopic boom as claimed in one of claims 1-4, characterized in that the locking device is arranged on the inside on the upper side of the telescopic stage (4) that can be angled.
 6. The telescopic boom as claimed in one of claims 1-5, characterized in that the locking device is formed by one or more hydraulic cylinder-piston systems which are attached to the inner side of the two portions (4 a, b).
 7. The telescopic boom as claimed in one of claims 1-5, characterized in that the locking device is formed by one or more threaded spindle drives which are attached to the inner side of the two portions (14 a, b).
 8. The telescopic boom as claimed in one of claims 1-5, characterized in that the locking device is formed as a pin locking system.
 9. The telescopic boom as claimed in claim 8, characterized in that in the locking device, at least one locking pin, in particular a pair of locking pins (16 a, b), are provided which pins, given a coaxial alignment of the longitudinal axes of the portions (4 a, b), are capable in each case of being inserted into coaxial drilled holes in a locking fork (18 a, b) which is connected to one portion (4 a), and a locking lug (17 a, b) which is connected to the other portion (4 b), in order to, achieve a locking of this coaxial alignment, and capable of being withdrawn from the drilled holes, canceling the locking.
 10. The telescopic boom as claimed in one of claims 8-9, characterized in that, in order to fix an angled position of the two portions (4 a, b), the locking device has a retaining lug (20) which in each case is connected by retaining pins (19 a, b) to a retaining fork (21 a, b) which, on the inside, is in each case fixed to one of the two portions (14 a, b).
 11. The telescopic boom as claimed in claim 10, characterized in that the retaining lug (20) has a slot (31) in which the retaining pins (19 a, b) can slide.
 12. The telescopic boom as claimed in one of claims 8-11, characterized in that the locking pins (16 a, b) are in each case fixed to a pin carrier (23 a, b) which can be moved parallel to the axes of the drilled holes in the locking forks (18 a, b) and locking lugs (17 a, b).
 13. The telescopic boom as claimed in claim 12, characterized in that the pin carriers (23 a, b) can be moved by means of a threaded spindle drive (24, 25 a, b).
 14. The telescopic boom as claimed in one of claims 12-13, characterized in that the pin carriers (23 a, b) can be moved by means of a hydraulic, pneumatic, electric-motor or electromagnetic drive.
 15. The telescopic boom as claimed in claim 13, characterized in that the threaded spindle drive (24, 25 a, b) can be rotated by means of a hand crank (26).
 16. The telescopic boom as claimed in claim 15, characterized in that the hand crank (26) has a drive shaft (28) which can be displaced axially in a corresponding hollow shaft belonging to the threaded spindle drive (adjusting shaft 24) and is firmly guided in the latter so as to rotate with it.
 17. The telescopic boom as claimed in one of claims 15-16, characterized in that the hand crank (26) has a handle that can be folded in. 